1. Field of the Invention
The present invention relates to a variable speed ratchet wrench, and in particular to a variable speed ratchet wrench using a planetary gear arrangement.
2. Background of the Technology
Speed wrenches with planetary gear arrangements are known in the prior art. However, the wrenches of the prior art are difficult to operate. In addition, they include complex mechanical components, which make the wrench difficult and more expensive to operate, construct, maintain and repair.
3. Description of Related Art
U.S. Pat. No. 1,762,515 to Hiersch discloses a speed wrench. To get a one-to-one geared speed, the operator presses downwardly on the operating handle. To get enhanced geared speed, the downward pressure is released on the handle and the speed changing device is restored to its normal position.
U.S. Pat. No. 2,520,443 to Seaguist discloses a planetary gear speed wrench. To get a one-to-one geared speed, the wrench is inverted and the operator holds a first handle and rotates a second handle. To get enhanced geared speed: the second handle is held stationary by the operator, and the first handle is revolved; the first handle is held stationary and the second handle is revolved, or both the first handle and the second handle may be rotated simultaneously relative to one another in opposite directions.
U.S. Pat. No. 2,634,630 to Johnson discloses a geared wrench that can be used as a multiple rotational advantage ratchet type of wrench for both loosening and tightening operations. To use the assembly as a multiple rotational wrench for a tightening operation, the handle is grasped in the operator""s hand. The auxiliary handle is then grasped in the operator""s other hand. The auxiliary handle is then reciprocated while the handle is held stationary. The operator can hold the auxiliary handle stationary and reciprocate the wrench handle with his other hand, and thereby achieve the same results. To use the assembly as a one-to-one wrench without the ratchet action, the wrench handle and the auxiliary handle are rotated together.
U.S. Pat. No. 3,945,274 to Annett discloses a speed wrench where, if the hand grip is held against rotation by the operator while the handle is turned, the output will be driven at a speed greater than that of the handle. If the resistance offered by the driven object becomes large enough so that the hand grip may not conveniently be held, the operator may release the hand grip or slacken his hold thereof thus allowing the ratchet to engage and lock the handle to the output so that the handle will directly drive the output.
There is a present need for a simpler variable speed ratchet wrench.
The present invention provides a variable speed ratchet wrench that is simpler than the prior art, and functions logically based on existing standard ratchet wrench operation. The fact that the present invention is simpler has many benefits over the prior art, including, but not limited to: easier manufacture, less-costly manufacture, easier operation, easier maintenance, and easier repair.
An embodiment of the present invention comprises a variable speed ratchet wrench having: a main handle portion with an opening for receiving a planetary gear mechanism, a planetary gear mechanism with a locking device attached to the output shaft for driving wrench fittings, and a planetary gear housing cover having an attached secondary handle that controls operation via the planetary gears. The locking device has two positions, such that ratching action is achievable for both clockwise and counterclockwise driving. The secondary handle selectively revolves the planetary gears relative to the sun gear in an unlocked position and prevents the planetary gears from revolving about the sun gear in a locked position, thereby selectively providing a geared speed increase in the driven speed of the output shaft.
In an embodiment of the present invention, the planetary gear mechanism includes a sun gear, two interconnected planetary gears, and a ring gear for driving the output shaft, such that the direction of motion of the handle and ring gear match the direction of motion of the output shaft. The sun gear is intermeshed with the first planetary gear, the first planetary gear is intermeshed with the second planetary gear, and the second planetary gear is intermeshed with inner teeth of the ring gear, such that rotational motion of the sun gear is in the same direction as the ring gear, in contrast to speed wrenches of the prior art. This feature allows use of the ratchet in a manner similar to typical non-speed ratchet wrenches.
To get a one-to-one drive with a ratchet function in an embodiment of the present invention, the secondary handle is locked into position against the main handle, thereby locking the planetary gears to prevent revolution about the sun gear. To obtain a geared speed enhancement with a ratchet function, the operator releases the secondary handle from the main handle, and the relative motion of the main and secondary handles allows the planetary gears to revolve about the sun gear.
Additional advantages and novel features of the invention will be set forth in part in the description that follows, and in part will become more apparent to those skilled in the art upon examination of the following or upon learning by practice of the invention.